Modulatory effects of repetitive peripheral magnetic stimulation on the soleus H-reflex: comparison between peripheral nerve and motor point stimulation

[Purpose] We compared the effects of repetitive peripheral magnetic stimulation (rPMS) applied to the peripheral nerve and motor points on the H-reflex pathway in the soleus muscle. [Participants and Methods] Thirty-six healthy adult males were randomly assigned to one of three groups: peripheral nerve stimulation, motor point stimulation, or control (n=12/group). The excitability of the monosynaptic reflex pathway was assessed using the H-reflex of the soleus muscle. In each session, 24 H-reflexes were recorded 10 min before and after either rPMS or rest (control groups). The final analysis was carried out by comparing the mean amplitudes of the resulting 12 measurements. [Results] The H-reflex amplitude increased following stimulation in the peripheral nerve stimulation group, and a significant interaction effect was observed among the three groups (before and after intervention in the peripheral nerve and motor point stimulation groups, and 10 min before and after rest in the control group). [Conclusion] The increase in H-reflex amplitude after peripheral nerve stimulation may be attributed to effective stimulation of the tibial nerve, with signals ascending through Ia sensory fibers. Future research should clarify the mechanism by which rPMS influence spinal neural circuits via peripheral nerves and muscles.